1. Field of the Invention
The present invention relates to a wireless terminal device that can communicate in a plurality of communication systems, and to a method of controlling the wireless terminal device.
2. Related Art
In recent years, in addition to a communication system of a 3G standard (for example, CDMA) that is a CS (Circuit Switched) standard, a communication system of an LTE (Long Term Evolution) standard has been introduced as a communication system utilized by a wireless terminal device such as a cellular telephone device.
A CS Fallback function is defined in 3GPP TS 23.272, and by way of this function, an incoming call request from the CDMA can be reported via the LTE system (for example, see Japanese Unexamined Patent Application, Publication No. 2009-267996, and 3GPP TS 23.272 V10.1.0, “Circuit Switched (CS) fallback in Evolved Packet System (EPS), Stage2” 2010-09).